How to fix the unexpected end of subtree error

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The “unexpected end of subtree” error is most commonly thrown in programming when your code is a missing or incomplete block. The more complex the code you have written the more chances there will be that a mistake has been made at some point in the syntax. As each code is different, and a syntax error could refer to any portion of your code, there is also no quick one-step solution that you can employ to solve it. Instead, you will most likely be required to look through your entire code to determine what possible mistakes have been made.

What does the “unexpected end of subtree” error code mean?

The error message indicates that the compiler or parser has reached the end of a section of code (subtree) and is looking for further content. However, instead of finding additional content it either reached the end of the file or some unexpected termination.

How can you fix the “unexpected end of subtree” error code?

Review your HQL Syntax

As this error code in Hibernate will usually be thrown when there are issues with your Hibernate Query Language (HQL) or Criteria API queries, the first thing to check is your syntax.

String hqlQuery = "SELECT p FROM consumer p WHERE p.age > :minage AND ";

The above query is incomplete and it will give you the error “unexpected end of subtree“. Instead complete the query properly as below

String hqlQuery = "SELECT p FROM consumer p WHERE p.age > :minage AND p.category = :approvedCategory";

Few more points to be noted

When reviewing your syntax, it is important to double-check all spaces, commas, and other punctuation marks. These are the most common areas where such mistakes might have been made. However, in fixing syntax issues there are also several other steps you can take, these include:

Using Aliases

When using aliases for entities you need to ensure both their proper definition and usage.

Association Types

If your code includes associations between different entities, make sure you use the proper syntax for fetches and joins. If you are not sure about the different association types then you must look into them so you can gain a better understanding of how to properly use them.

Parameter Binding

When it comes to parameters you need to ensure that the parameter names are in alignment with the names used in your code. The parameters will also need to be bound correctly for the code to work.

Check your Opening and Closing symbols

Since the subtree error directly references that at the end of a section of code your compiler was looking for the continuation, it is likely that the problem has occurred from one of your parentheses, braces, or brackets missing.

Essentially this means that you will need to look through your code to ensure that every opening parenthesis ‘()’, brace ‘{}’, and bracket ‘[]’ symbol has its corresponding closing symbol.

Example:

if x > 0:
        print("Positive number."

The above code will return “unexpected end of subtree“. To fix this make sure to close the bracket properly

if x > 0: 

print("Positive number.")

Testing

Part of the way to fix the problem is to locate where it is. To do that more easily you have a few options, the most popular of which include either testing a simplified query or testing incrementally.

In cases of issues testing a simpler query and then gradually adding to its complexity while testing at each stage could help you identify exactly where the syntax error is. Once the error has been found it will be much easier for you to solve the issue.

Review Quotes and String Delimiters

Much like with the brackets and parentheses, you will also need to make sure that none of your strings are properly enclosed in quotes. This includes having no unclosed or mismatched quotes.

Check the Criteria API Code

Incomplete or missing expressions in your code could often result in the subtree error appearing. As such, if you are working with Criteria API you will need to take the time to review your queries and check that you have applied all the required restrictions and conditions. Without these, the error message will continue appearing.

Use Proper Indentation

Code blocks are usually defined by proper indentation, this could mean that if the code is not indented properly and each block is not properly nested in its parent block then the code will run properly.

Example: The following code had the bad indentation


def example_function(x):
    if x > 0:
        print("Positive number.")
    else:
        if x == 0:
            print("Zero.")
        else:
            print("Negative number.")
  # The following line has incorrect indentation and may cause an error
  print("End of function.")

To resolve this, Make sure to keep the space appropriate

def example_function(x):
    if x > 0:
        print("Positive number.")
    else:
        if x == 0:
            print("Zero.")
        else:
            print("Negative number.")
    # Corrected indentation
    print("End of function.")

Conclusion

While at first glance a subtree error might seem intimidating there are several different steps you can take to find the error and address it accordingly. Focusing on your syntax you should be able to swiftly locate the error using the list above.

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Jerry Richard

Cloud Premier Engineer at Cloudera

Jerry grew up in a small town where he enjoyed playing video games. Once out of the nest, he pursued a Bachelor's degree in Computer Engineering. After college, he ultimately landed in the IT industry. Currently, he has over 10 years of experience. In his spare time, Jerry enjoys spending time with his family.

He is creator of this website - unexpectedendoffile.com, A website dedicated to share the mistake and experience learned.